[Cronet] Move initialization to a new thread rather than the UI thread.

net/proxy/proxy_config_service_android_unittest.cc

Index: net/proxy/proxy_config_service_android_unittest.cc
diff --git a/net/proxy/proxy_config_service_android_unittest.cc b/net/proxy/proxy_config_service_android_unittest.cc
index 4692553212d5f9d51684cebe58c49ba078dd1231..f1b3ddf7120829b3fe4bc18f3a3de8889a2bf6fc 100644
--- a/net/proxy/proxy_config_service_android_unittest.cc
+++ b/net/proxy/proxy_config_service_android_unittest.cc
@@ -12,6 +12,7 @@
 #include "base/compiler_specific.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
+#include "jni/AndroidProxyConfigServiceTestUtil_jni.h"
 #include "net/proxy/proxy_config.h"
 #include "net/proxy/proxy_info.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -45,6 +46,15 @@ class TestObserver : public ProxyConfigService::Observer {
   ProxyConfigService::ConfigAvailability availability_;
 };
 
+// Helper class that simply prepares Java's Looper on construction.
+class JavaLooperPreparer {
+ public:
+  JavaLooperPreparer() {
+    Java_AndroidProxyConfigServiceTestUtil_prepareLooper(
+        base::android::AttachCurrentThread());
+  }
+};
+
 }  // namespace
 
 typedef std::map<std::string, std::string> StringMap;
@@ -56,6 +66,9 @@ class ProxyConfigServiceAndroidTestBase : public testing::Test {
   ProxyConfigServiceAndroidTestBase(const StringMap& initial_configuration)
       : configuration_(initial_configuration),
         message_loop_(base::MessageLoop::current()),
+        // Prepare Java's Looper before constructing |service_| as it creates
+        // ProxyChangeListener which requires a Looper.
+        java_looper_preparer_(),

[xunjieli, 2017/04/13 18:44:54]

hmm.. I guess this isn't safe to omit? I'd assume the compiler initializes
|java_looper_preparer_| before |service_| because that's the order specified
below.

[pauljensen, 2017/05/01 15:35:53]

You're right, I think I put it here so the comment would precede the |service_|
initializer call.  I've now moved the comment to java_looper_preparer_
declaration.

         service_(message_loop_->task_runner(),
                  message_loop_->task_runner(),
                  base::Bind(&ProxyConfigServiceAndroidTestBase::GetProperty,
@@ -104,6 +117,7 @@ class ProxyConfigServiceAndroidTestBase : public testing::Test {
   StringMap configuration_;
   TestObserver observer_;
   base::MessageLoop* const message_loop_;
+  JavaLooperPreparer java_looper_preparer_;
   ProxyConfigServiceAndroid service_;
 };